It is known that, in a typical back-pack engine blower, a space between a back support of a frame and a volute case is covered by a dustproof cover called a free flow net (for instance, Patent Literature 1). The dustproof cover is disposed away from an air intake port of the volute case. Accordingly, unlike an arrangement in which the air intake port is directly covered by the dustproof cover, air intake is not disturbed and a sufficient air flow is obtainable. Moreover, in the dustproof cover disposed away from the air intake port, suction acting on the dustproof cover is not so large. Accordingly, fallen leaves and the like do not stick to a surface of the dustproof cover. Even if fallen leaves and the like stick thereto during operation, when a flow rate is further decreased by returning an engine to an idling condition, fallen leaves more easily unstick from this dustproof as compared with a typical guard net. Consequently, necessary air flow can be reliably maintained.
In the engine blower, some of the air sucked into the volute case is taken out through an outlet provided at a part of the volute case and is used as cooling air for the engine (hereinafter simply referred to as cooling air) and intake air for engine combustion (hereinafter simply referred to as intake air). Since the air sucked into the volute case is circulated in a circumferential direction along a shape of the volute case, dust and the like sucked together with air is centrifuged outward and an inner air including relatively less dust is used as the cooling air and the intake air.